How Kubernetes Services Really Work - iptables, kube-proxy, and Packet Flow Explained

Discover how Kubernetes Service networking actually works at the kernel level. This deep-dive tutorial demystifies the Linux netfilter framework, iptables, and kube-proxy to reveal the exact mechanisms behind container networking.

You'll learn:
- The 5 netfilter hooks and how packets traverse the kernel networking stack
- When packets hit PREROUTING, INPUT, FORWARD, OUTPUT, and POSTROUTING chains
- How iptables tables (filter, nat, mangle) organize firewall and NAT rules
- DNAT vs SNAT and why they operate at different hooks
- How kube-proxy translates Service ClusterIPs to Pod IPs using iptables chains
- Connection tracking (conntrack) and automatic reverse NAT
- Docker's FORWARD chain security model and DOCKER-USER usage

Hands-on demonstrations:
1. Tracing packet flow through netfilter hooks with kernel logs
2. Implementing DNAT for port forwarding with Docker containers
3. Inspecting real kube-proxy iptables rules in a Kubernetes cluster

By the end, you'll understand why Service connectivity fails, how to debug iptables rules with packet counters, and the exact chain hierarchy that kube-proxy creates for load balancing.

Perfect for DevOps engineers, SREs, and Kubernetes administrators.

Видео How Kubernetes Services Really Work - iptables, kube-proxy, and Packet Flow Explained канала MattOps | DevOps & SRE